Acral multiple symmetrical palisaded encapsulated neuromas: A rare case report and review of the literature.

Palisaded encapsulated neuroma (PEN) is a benign neoplasm composed of nerve tissue. It typically presents as isolated, asymptomatic, skin-colored papules or nodules on the face, neck, or oral mucosa of the middle-aged and elderly. Here, we reported a very unusual and unique case of acral multiple symmetrical PENs with no obvious systemic abnormalities and reviewed the published work on acral PEN.

Pathologic remodeling in human neuromas: insights from clinical specimens.

BACKGROUND: Neuroma pathology is commonly described as lacking a clear internal structure, but we observed evidence that there are consistent architectural elements. Using human neuroma samples, we sought to identify molecular features that characterize neuroma pathophysiology. METHODS: Thirty specimens-12 neuromas-in-continuity (NICs), 11 stump neuromas, two brachial plexus avulsions, and five controls-were immunohistochemically analyzed with antibodies against various components of normal nerve substructures. RESULTS: There were no substantial histopathologic differences between stump neuromas and NICs, except that NICs had intact fascicle(s) in the specimen. These intact fascicles showed evidence of injury and fibrosis. On immunohistochemical analysis of the neuromas, laminin demonstrated a consistent double-lumen configuration. The outer lumen stained with GLUT1 antibodies, consistent with perineurium and microfascicle formation. Antibodies to NF200 revealed small clusters of small-diameter axons within the inner lumen, and the anti-S100 antibody showed a relatively regular pattern of non-myelinating Schwann cells. CD68+ cells were only seen in a limited temporal window after injury. T-cells were seen in neuroma specimens, with both a temporal evolution as well as persistence long after injury. Avulsion injury specimens had similar architecture to control nerves. Seven pediatric specimens were not qualitatively different from adult specimens. NICs demonstrated intact but abnormal fascicles that may account for the neurologically impoverished outcomes from untreated NICs. CONCLUSIONS: We propose that there is consistent pathophysiologic remodeling after fascicle disruption. Particular features, such as predominance of small caliber axons and persistence of numerous T-cells long after injury, suggest a potential role in chronic pain associated with neuromas.

Characterization of neuromas in peripheral nerves and their effects on heterotopic bone formation.

The formation of neuromas involves expansion of the cellular components of peripheral nerves. The onset of these disorganized tumors involves activation of sensory nerves and neuroinflammation. Particularly problematic in neuroma is arborization of axons leading to extreme, neuropathic pain. The most common sites for neuroma are the ends of transected nerves following injury; however, this rodent model does not reliably result in neuroma formation. In this study, we established a rodent model of neuroma in which the sciatic nerve was loosely ligated with two chromic gut sutures. This model formed neuromas reliably (∼95%), presumably through activation of the neural inflammatory cascade. Resulting neuromas had a disorganized structure and a significant number of replicating cells. Quantification of changes in perineurial and Schwann cells showed a significant increase in these populations. Immunohistochemical analysis showed the presence of ß-tubulin 3 in the rapidly expanding nerve and a decrease in neurofilament heavy chain compared to the normal nerve, suggesting the axons forming a disorganized structure. Measurement of the permeability of the blood-nerve barrier shows that it opened almost immediately and remained open as long as 10 days. Studies using an antagonist of the ß3-adrenergic receptor (L-748,337) or cromolyn showed a significant reduction in tumor size and cell expansion as determined by flow cytometry, with an improvement in the animal's gait detected using a Catwalk system. Previous studies in our laboratory have shown that heterotopic ossification is also a result of the activation of neuroinflammation. Since heterotopic ossification and neuroma often occur together in amputees, they were induced in the same limbs of the study animals. More heterotopic bone was formed in animals with neuromas as compared to those without. These data collectively suggest that perturbation of early neuroinflammation with compounds such as L-748,337 and cromolyn may reduce formation of neuromas.

Analysis of regeneration- and myelination-associated proteins in human neuroma in continuity and discontinuity.

BACKGROUND: Neuromas are pathologic nerve distensions caused by a nerve's response to trauma, resulting in a dysfunctional to non-functional nerve. Depending on the severance of the affected nerve, the resulting neuroma can be differentiated into continuous and stump neuroma. While neuroma formation has been investigated in animal models with enormous regenerative capacity, the search for differences in human response to nerve trauma on a molecular level ultimately seeks to identify reasons for functionally successful versus unsuccessful regeneration after peripheral nerve trauma in man. METHODS: In the present study, the regenerative potential of axons and the capability of Schwann cells (SC) to remyelinate regenerating axons was quantitatively and segmentally analyzed and compared within human neuroma in-continuity and discontinuity. RESULTS: For the stump neuroma and the neuroma in-continuity, there was a significant reduction of the total number of axons (86% stump neuroma and 91% neuroma in-continuity) from the proximal to the distal part of the neuroma, while the amount of fibrotic tissue increased, respectively. Labeling the myelin sheath of regenerating axons revealed a remyelination of regenerating axons by SCs in both neuroma types. The segmented analysis showed no distinct alterations in the number and spatial distribution of regenerating, mature, and myelinated axons between continuous and discontinuous neuroma. CONCLUSIONS: The quantitative and segmented analysis showed no distinct alterations in the number and spatial distribution of regenerating, mature, and myelinated axons between continuous and discontinuous neuroma, while the extensive expression of Gap43 in up to 55% of the human neuroma axons underlines their regenerative capacity independent of whether the neuroma is in continuity or discontinuity. Remyelination of Gap43-positive axons suggests that the capability of SCs to remyelinate regenerating axons is preserved in neuroma tissue.

Swimming Training Reduces Neuroma Pain by Regulating Neurotrophins.

INTRODUCTION: Neuroma formation after peripheral nerve transection leads to severe neuropathic pain in amputees. Previous studies suggested that physical exercise could bring beneficial effect on alleviating neuropathic pain. However, the effect of exercise on neuroma pain still remained unclear. In addition, long-term exercise can affect the expression of neurotrophins (NT), such as nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF), which play key roles in nociceptor sensitization and nerve sprouting after nerve injury. Here, we investigated whether long-term swimming exercise could relieve neuroma pain by modulating NT expression. METHODS: We used a tibial neuroma transposition (TNT) rat model to mimic neuroma pain. After TNT surgery, rats performed swimming exercise for 5 wk. Neuroma pain and tactile sensitivities were detected using von Frey filaments. Immunofluorescence was applied to analyze neuroma formation. NGF and BDNF expressions in peripheral neuroma, dorsal root ganglion, and the spinal cord were measured using enzyme-linked immunosorbent assay and Western blotting. RESULTS: TNT led to neuroma formation, induced neuroma pain, and mechanical allodynia in hind paw. Five-week swimming exercise inhibited neuroma formation and relieved mechanical allodynia in the hind paw and neuroma pain in the lateral ankle. The analgesic effect lasted for at least 1 wk, even when the exercise ceased. TNT elevated the expressions of BDNF and NGF in peripheral neuroma, dorsal root ganglion, and the spinal cord to different extents. Swimming also decreased the elevation of NT expression. CONCLUSIONS: Swimming exercise not only inhibits neuroma formation induced by nerve transection but also relieves pain behavior. These effects might be associated with the modulation of NT.

Hyaluronic acid/carboxymethyl cellulose directly applied to transected nerve decreases axonal outgrowth.

Neuroma management is an unresolved problem. Biomaterials to limit unwanted axonal growth could be a tool to manage neuroma. Hyaluronic acid/carboxymethyl cellulose (HA/CMC) is an antiadhesive, biodegradable material that is nontoxic to nerve. The purpose of this study was to evaluate the efficacy of this biomaterial to limit axonal growth. Rats received a sciatic nerve transection and repair with a short conduit (5 mm) containing HA/CMC, fibrin, or nothing (empty conduit). In another study, nerve was transected and either left undisturbed or wrapped with HA/CMC around the proximal and distal ends. In a final study, nerve was transected and repaired with an HA/CMC wrap. Four weeks following the procedures, nerves were harvested and assessed using histomorphometry to measure axonal regeneration. Axonal regeneration following transection was significantly inhibited by direct axonal contact with HA/CMC, whether within a conduit or wrapped around the transected proximal nerve end. Axonal regeneration following epineurial repair was not affected by HA/CMC wrapped around nerve, demonstrating axonal growth inhibition due to direct contact of regenerating axons with HA/CMC. These studies demonstrate the efficacy of HA/CMC to limit axonal outgrowth by contact with regenerating axons. HA/CMC barriers may prove to be a tool to prevent neuroma formation by inhibiting axonal growth. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 568-574, 2017.

Significance of alpha smooth muscle actin expression in traumatic painful neuromas: a pilot study in rats.

Treatment of painful neuromas remains a challenge and the mechanism of neuroma-associated pain is not yet fully understood. In this study, we aimed to observe the expression of alpha smooth muscle actin (α-SMA) in traumatic neuromas and to investigate its possible roles in the cause of neuropathic pain in a rat model. The rat sciatic nerve was used and the experiment was divided into two parts. In part I, our results showed significantly higher levels of α-SMA and the pain marker c-fos in the autotomy group than in the no-autotomy group. In part II, the expression of α-SMA in neuromas was down- and up-regulated using SB-431542 and GW9662, respectively. A significant correlation between autotomy scores and the expression level of α-SMA was found (R = 0.957; p < 0.001) and the expression level of α-SMA was positively related to the autotomy scores (R(2) = 0.915, p < 0.001). We concluded that the expression of α-SMA plays certain roles in the neuroma-associated pain, either as a direct cause of pain or as an indirect marker of existence of local mechanical stimuli. Our findings may provide new insights into the development of new treatment modalities for the management of intractable painful neuromas.

Multiple palisaded encapsulated neuromas in siblings: A case report and review of the published work.

Palisaded encapsulated neuroma (PEN) is an uncommon, typically solitary, cutaneous neural neoplasm. Multiple mucocutaneous neuromas are usually seen in multiple endocrine neoplasia (MEN) 2b syndrome. Multiple cutaneous PEN in adult patients with or without features of MEN 2b are extremely rare, with only a few cases described. We report a case of multiple PEN in siblings of the same family with no apparent systemic abnormalities, and review the relevant published work to explore its clinical and pathogenic features and the relationship between multiple PEN and MEN 2b type neuroma (multiple mucocutaneous neuromas seen in MEN 2b syndrome).

Peripheral Nerve Sheath Tumors of the Eyelid Dermis: A Clinicopathologic and Immunohistochemical Analysis.

PURPOSE: To determine the incidences, clinical features, and detailed histopathologic and immunohistochemical findings of 10 peripheral nerve tumors (isolated neurofibromas, solitary circumscribed neuromas [SCNs], and schwannomas) localized to the eyelid dermis. METHODS: In this retrospective clinicopathologic study, clinical records and paraffin sections subjected to hematoxylin and eosin, Masson trichrome, periodic acid-Schiff, reticulin, and Alcian blue staining were critically reviewed from each case. Additional paraffin sections were immunoreacted for S100, neurofilament, CD34, epithelial membrane antigen (EMA), glucose transporter-1 (glut-1), and calretinin. RESULTS: Ten patients with a median age of 57 years had solitary, small, flesh-colored papules, 70% at the eyelid margin. Microscopically, they were diagnosed either as a SCN or an isolated neurofibroma. SCN was diffusely S100-positive (and sometimes diffusely calretinin-positive) with myriad neurofilaments. Fascicles of cells were separated by CD34-positive septa, and the lesions were surrounded by a glut-1/EMA-positive capsule. Neurofibromas were calretinin-negative and had a moderate number of S100-positive cells, with widely scattered neurofilaments, many CD34-postive intermixed cells, and no capsule. No schwannomas were diagnosed. CONCLUSIONS: Peripheral nerve tumors of the eyelid have a distinct clinical presentation at the eyelid margin. Careful histopathologic and immunohistochemical studies can reliably separate the entities in the categories of isolated neurofibroma, SCN, and schwannoma when the last occurs. These distinctions can have important systemic implications.

Immunohistochemical Analysis of the Structure of Injured Peripheral Nerve Neuroma after Electrosurgical Welding Intervention.

Immunohistochemical analysis of changes in neuroma after surgical treatment of damaged peripheral nerve with the use of high frequency electrosurgical device for high frequency current welding of soft tissues was carried out. No adverse effects of this technology and the bipolar instrument on degeneration and regeneration of damaged nerve stem were detected.

Perineural growth of benign cutaneous sweat gland tumors: a hitherto unrecognized phenomenon unassociated with malignancy.

BACKGROUND: Cutaneous intraneural reactive epithelial proliferations mimicking malignancy include epithelial sheath neuroma, re-excision perineural invasion and reactive neuroepithelial aggregates. Nevertheless, intraneural growth of benign sweat gland tumors has not been reported before. AIMS: To report a predominantly intraneural proliferation of morphologically bland sweat gland tumors, describe their clinicopathological features and correlate them with survival. RESULTS: We analyzed a spiradenoma and a hidradenoma with a prominent intraneural growth, occurring on the back of the 19-year-old woman and on the arm of the 53-year-old woman. Both lesions presented as a painful and slightly raised papule. After complete excision, an uneventful clinical course was observed during the follow-up period of 52 and 54 months. Pathologically, the most striking feature was an almost exclusive intraneural growth within the peripheral nerves of the deep dermis and subcutis. CONCLUSION: We report for the first time the predominantly intraneural growth of benign sweat gland tumors. Although their histogenesis is unknown, perineural displacement due to previous surgery or trauma, as well as development from intraneural embryological epithelial remnants remains possibilities. Long-term follow-up of our patients suggests that intraneural growth of otherwise bland sweat gland tumors does not signify malignancy. Complete excision appears to be sufficient treatment procedure.

Expression of heat shock proteins in brain tumors.

AIM: Heat shock proteins (HSP) are an evolutionary conserved family of proteins that serve as molecular chaperones, preventing the formation of nonspecific protein aggregates and assisting proteins in the acquisition of their native structures. Furthermore, HSPs have anti-apoptotic properties and have been found to be elevated in many human cancers; their overexpression has been associated with poor survival and response to therapy. In the present study we assessed the HSP expression in brain tumors. MATERIAL AND METHODS: Simultaneous detection of HSP27, HSP40, HSP60, HSP70, HSP90a, total Akt and phospho- Akt in 19 brain tumor specimens was performed using the multiplex bead array assay. RESULTS: There was expression of HSP27 (pSer82), HSP27 (pSer15), HSP40, HSP60, HSP70, HSP90a, total-Akt and phospho- Akt in both gliomas and meningiomas. Significantly higher levels of HSP70 and a trend towards higher levels of HSP40 were found in meningiomas compared to gliomas. There was a significant correlation between HSP27 (pSer82) and HSP27 (pSer15) expression and between HSP90a and both total-AKT and phospho- AKT. A significant correlation between HSP27 and total-AKT was observed. CONCLUSION: Since HSPss are an attractive target for anticancer therapy, further studies are needed in order to better assess their relationship with tumor aggressiveness and patient prognosis.

Correlation of Nav1.8 and Nav1.9 sodium channel expression with neuropathic pain in human subjects with lingual nerve neuromas.

BACKGROUND: Voltage-gated sodium channels Nav1.8 and Nav1.9 are expressed preferentially in small diameter sensory neurons, and are thought to play a role in the generation of ectopic activity in neuronal cell bodies and/or their axons following peripheral nerve injury. The expression of Nav1.8 and Nav1.9 has been quantified in human lingual nerves that have been previously injured inadvertently during lower third molar removal, and any correlation between the expression of these ion channels and the presence or absence of dysaesthesia investigated. RESULTS: Immunohistochemical processing and quantitative image analysis revealed that Nav1.8 and Nav1.9 were expressed in human lingual nerve neuromas from patients with or without symptoms of dysaesthesia. The level of Nav1.8 expression was significantly higher in patients reporting pain compared with no pain, and a significant positive correlation was observed between levels of Nav1.8 expression and VAS scores for the symptom of tingling. No significant differences were recorded in the level of expression of Nav1.9 between patients with or without pain. CONCLUSIONS: These results demonstrate that Nav1.8 and Nav1.9 are present in human lingual nerve neuromas, with significant correlations between the level of expression of Nav1.8 and symptoms of pain. These data provide further evidence that changes in expression of Nav1.8 are important in the development and/or maintenance of nerve injury-induced pain, and suggest that Nav1.8 may be a potential therapeutic target.

Malignant peripheral nerve sheath tumor arising in a traumatic neuroma: a case report.

A 67-year-old woman with a history of breast cancer presented with a soft tissue mass at the site of a remote, non-neoplastic lumbar surgery. Excisional biopsy revealed a traumatic neuroma. Five years later she re-presented with a rapidly growing, tender nodule at the same site. An excisional biopsy was again performed and revealed a tumor composed of malignant epithelioid and spindle cells merging imperceptibly with residual traumatic neuroma. The malignant cells were positive for vimentin, S-100 and micropthalmia transcription factor. They were negative for cytokeratins, muscle markers, Melan-A, HMB45, glial fibrillary acidic protein, and myelin basic protein. Electron microscopy showed no melanosomes. The diagnosis of malignant peripheral nerve sheath tumor arising within a long-standing traumatic neuroma was rendered and represents a hitherto unreported origin of this rare, aggressive soft tissue sarcoma.

Expression of c-Jun and Sox-2 in human schwannomas and traumatic neuromas.

AIMS: Schwann cells myelinate axons of the peripheral nervous system. This process of myelination is regulated by various transcription factors. c-Jun and Sox-2 are negative regulators of myelination and control Schwann cell differentiation and plasticity. Schwannoma cells within tumours no longer express myelin markers, and show increased proliferation and decreased apoptosis. We have shown previously that several signalling pathways are activated in schwannoma cells in situ, in particular the c-Jun N-terminal kinase (JNK) pathway. Both in vitro and in vivo we have demonstrated that c-Jun and Sox-2 are co-regulated in Schwann cells and evidence shows that both these proteins regulate myelination negatively. In this study, we aimed to characterize the expression of c-Jun and Sox-2 in schwannoma and traumatic neuroma. METHODS AND RESULTS: Immunohistochemistry using antibodies to c-Jun and Sox-2 was applied to six schwannomas, and the results were compared with those seen in traumatic neuroma and normal nerve. Increased expression of c-Jun and Sox-2 was seen in schwannoma. CONCLUSIONS: We have demonstrated increased expression of c-Jun and Sox-2 in schwannoma compared to traumatic neuroma. There was no expression of c-Jun and Sox-2 in a histologically normal peripheral nerve.

The expression of α-SMA in the painful traumatic neuroma: potential role in the pathobiology of neuropathic pain.

The exact mechanism of neuroma-associated pain is not yet fully understood, thus contributing to the substantial challenge faced in managing patients with painful neuromas. We aimed to observe the expression of alpha smooth muscle actin (α-SMA) in the painful traumatic neuroma and to investigate its possible roles in the cause of neuroma-associated pain. Its expression is considered to be a useful phenotypic marker for myofibroblast, and may contribute to its increased contractile activity. We collected peripheral neuroma specimens prospectively and subsequently divided them into two groups: painful (n=21) and non-painful (n=27) based on blinded preoperative visual analogue scale (VAS) pain scores. We also harvested normal nerve specimens from the discarded limbs as a control group (n=8). We performed immunohistological studies to observe the expression of α-SMA in each group, and calculated the expression level by a high-resolution pathological image analysis system. There was no positive staining of α-SMA observed in the control group, slight positive staining in the non-painful group, and obviously positive staining in the painful group. Pearson correlation analysis demonstrated that VAS scores were significantly associated with the expression intensity of α-SMA (R=0.831; p<0.001). Linear regression analysis indicated that the expression intensity of α-SMA was positively related to the scale of VAS (R(2)=0.691, p<0.001). These findings suggest that: 1) expression of α-SMA may play certain roles in painful traumatic neuroma, either as a direct cause of neuroma-associated pain or as an indirect marker of local mechanical stimuli, and 2) the presence of α-SMA in the painful group may provide rationale for transpositional procedures in the management of traumatic neuroma. The persistent existence of α-SMA in the painful group and the correlation with VAS scores may provide insight into the development of new therapeutic strategies.

Accumulation of Kv7.2 channels in putative ectopic transduction zones of mice nerve-end neuromas.

BACKGROUND: Modulation of M-type currents has been proposed as a new strategy for the treatment of neuropathic pain due to their role in regulating neuronal excitability. Using electrophysiological techniques we showed previously that the opening of Kv7 channels with retigabine, blocked ectopic discharges from axotomized fibers but did not alter transduction at intact skin afferents. We hypothesized that after nerve damage, accumulation of Kv7 channels in afferent fibers may increase M-type currents which then acquired a more important role at regulating fiber excitability. FINDINGS: In this study, we used an immunohistochemical approach to examine patterns of expression of Kv7.2 channels in afferent fibers after axotomy and compared them to patterns of expression of voltage gated Na+ channels (Nav) which are key electrogenic elements in peripheral axons known to accumulate in experimental and human neuromas.Axotomy induced an enlargement and narrowing of the nodes of Ranvier at the proximal end of the neuroma together with a dramatic demyelination and loss of structure at its distal end in which naked accumulations of Nav were present. In addition, axotomy also induced accumulations of Kv7.2 that co-localized with those of Nav channels. CONCLUSIONS: Whilst Nav channels are mandatory for initiation of action potentials, (i.e. responsible for the generation/propagation of ectopic discharges) an increased accumulation of Kv7.2 channels after axotomy may represent a homeostatic compensation to over excitability in axotomized fibers, opening a window for a peripheral action of M-current modulators under conditions of neuropathy.

Tratamientos del Neuroma de Morton / Treatment of Monton´s neuroma

Este artículo está basado en una exhaustiva revisión bibliográfica. Pretende dar a conocer los posibles tratamientos del Neuroma de Morton, que están al alcance del profesional, para escoger el más optimo para la resolución de la patología. La revisión bibliográfica se realizó consultando artículos publicados en revistas especializadas, libros y diferentes páginas de internet. La conclusión obtenida es que el diagnóstico correcto, mediante los test de exploración, es básico para erradicar la patología. El apoyo de las técnicas de diagnóstico complementario es necesario debido a las diferentes patologías que presentan una sintomatología similar. Por último, destacar que, concretar la etiología compresiva o degenerativa del nervio, nos facilita la elección del tratamiento más adecuado, ya sea incruento o quirúrgico (AU)

This article is based on an extensive literature review. It aims to show professionals the available treatments that are possible for Morton’s neuroma, in order for them to choose the best one to cure this condition. The literature review was carried out by consulting published papers in journals, books and several websites. The conclusion is that a correct diagnosis, through clinical examination, is essential to eradicate this condition. Complementary diagnostic techniques are necessary because there are different diseases that have similar symptoms. Finally, it is worth highlighting that, defining the degenerative or compression etiology of the nerve, makes it easier to choose the most appropriate treatment, whether it is non-invasive or surgical (AU)